[True]

If I checked the turn it would be to call. Villain thinks he has to protect here so has value against lone spades (in his opinion), he also thinks he might have a solid bluff as the king is a decent scare card that you have shown weakness against. The villain may think he is value betting / protecting / bluffing with any kind of mediocre hand that called the flop.

I do agree that some As-x are in his range, but how many As-x do you call a re-raise with preflop and what % of time do you just call the flop?